Roland Westrelin's weblog (Comments)https://blogs.oracle.com/roland/
Blog for rolanden-usCopyright 2014Sat, 18 Jan 2014 07:16:14 +0000Apache Roller BLOGS401ORA6 (20130904125427)https://blogs.oracle.com/roland/entry/tcp_and_real_time#comment-1280965873000Re: TCP and real-timeguestWed, 4 Aug 2010 23:51:13 +0000abcdefghijklmnopqrstuvwxyzhttps://blogs.oracle.com/roland/entry/64_bit_java_rts#comment-1258532287000Re: 64 bit Java RTSJohn DaltonWed, 18 Nov 2009 08:18:07 +0000I would like to see a trade-off analysis document for different scenarios whether to use C++ or Java RTS. The scenarios could be for different domains life financial applications-trading etc, space, telcom etc.
Thank you!https://blogs.oracle.com/roland/entry/64_bit_java_rts#comment-1254906169000Re: 64 bit Java RTSBertrand DelsartWed, 7 Oct 2009 09:02:49 +0000Hi Ashwin,
As stated in David Holmes's reply on the forum, adding NHRTs requires adding other things. It is hard to backport only part of JavaRTS into HotSpot... and this require some changes that can impact the throughput. Trying to mix them efficiently in a single source base may require some major code refactoring. Maintaining it will not be easy too. This is one of the reasons why JavaRTS is still based on Java5.
The good news is that openJDK will indeed come with more deterministic GCs (like Garbage First). However, openJDK might soon reach a limit where you will notice all the other determinism issues we had to fix in JavaRTS to achieve sub-millisecond pause times (including support for real-time priorities).https://blogs.oracle.com/roland/entry/64_bit_java_rts#comment-1252583265000Re: 64 bit Java RTSAshwin JayaprakashThu, 10 Sep 2009 11:47:45 +0000I thought I should provide a link to some questions I had raised, more than a year ago on the Forums - http://forums.sun.com/thread.jspa?threadID=5273570
Especially this question ( http://forums.sun.com/thread.jspa?messageID=10147047#10147047), which I'll quote here to save your time:
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What would be really useful would be some kind of control over the GC interruption. What's really frustrating about the GC is when we use JVMs with multi-Gigabyte Heaps (which are very common these days), some critical time dependent functionality like &quot;Cluster heartbeat timers&quot; get interrupted and such delays mess up the whole setup, even though the JVMs are still up and running. I'm sure such modules can use the non-Heap Threads - even Soft-realtime would suffice.
The &quot;direct memory access&quot; also sounds very good - especially if someone is planning to build some kind of Paging system for pure Java Databases/Caches etc. Explicit memory management is good, sometimes...
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What is your opinion? Is there anything planned for something like this?https://blogs.oracle.com/roland/entry/real_time_java_and_futexes#comment-1251422583000Re: Real-time Java and futexes on LinuxsandeshFri, 28 Aug 2009 01:23:03 +0000i want some more info about futex.https://blogs.oracle.com/roland/entry/performance_tools_and_realtime_java#comment-1212054848000Re: Performance tools and realtime JavaLuis Claudio R. GoncalvesThu, 29 May 2008 09:54:08 +0000Another nice tool, part of the newer releases of the RT patch is ftrace. Ftrace is the evolution of the old in-kernel latency_tracer tool. It provides means to observe system events latency, wakeup latency, IRQs off latencies, preempt off latencies, a detailed function call list during latency periods and a filtered version of it. Apart from the detailed function call list all the other options have minimal impact on performance.https://blogs.oracle.com/roland/entry/real_time_java_and_futexes#comment-1210862269000Re: Real-time Java and futexes on LinuxMichaelThu, 15 May 2008 14:37:49 +0000I mean of course, the KERNEL.
The comment's arent editable post-postinghttps://blogs.oracle.com/roland/entry/real_time_java_and_futexes#comment-1210828801000Re: Real-time Java and futexes on LinuxMichaelThu, 15 May 2008 05:20:01 +0000very interesting article.
But it's unclear wether this is only a &quot;small&quot; bug that would be fixed in the near future version of the SUNS RTJVM ?https://blogs.oracle.com/roland/entry/performance_tools_and_realtime_java#comment-1209786324000Re: Performance tools and realtime JavaFrank Ch. EiglerSat, 3 May 2008 03:45:24 +0000Roland, thanks for giving systemtap a try and for writing such fair commentary about it. I was not aware of specific deficiencies with RT locking, but we will investigate.